Draft controlled railway car spring arrangement

ABSTRACT

Non-variable-rate springs are provided at some bearing areas while adjustable springs are provided at other bearing areas to uniformly maintain the loadings on the axles at the forward end at substantially equal values under a tractive effort. Control means are connected to the adjustable means to vary the force of the adjustable springs in response to the tractive effort of the power unit.

United States Patent [1 1 (111 3,756,161

Loosli 51 Sept. 4, 1973 1 DRAFT CONTROLLED RAILWAY CAR [56] ReferencesCited SPRING ARRANGEMENT UNITED STATES PATENTS [75] Inventor: HugoLoosli, Winterthur, 3,429,454 2/1969 Glass et a1, 213/43 Switzerland2,861,523 11/1958 Berry 3,548,755 12 1970 L' h 105 136X [73] Assignee:Schweizerische Lokomotiv-und C gg igg ffs fg wmteflhur PrimaryExaminerGerald M. Forlenza Assistant Examiner l-loward Beltran [22]Filed: Nov. 10, 1971 Attorney l-lu gh A. Chapin and Francis C. Hand eta1.

[21] Appl. No.: 197,442

[57] ABSTRACT Non-variable-rate springs are provided at some bearing 30F A l orelgn pplc auon pnomy Data areas while adjustable springs areprovided at other NOV. 16, 1970 I Switzerland 16909/70 bearing areas touniformly maintain the i g n the axles at the forward end atsubstantially equal values [52] Cl g ,25 374 under a tractive effort.Control means are connected to the adjustable means to vary the force ofthe adjustable [51] T Cl 861d 43/00 5/00 861g 9/00 springs in responseto the tractive effort of the power Field of Search /73, 136, 215, unit10 Claims, 5 Drawing Figures DRAFT CONTROLLED RAILWAY CAR SPRINGARRANGEMENT This invention relates to a rail motive power unit andparticularly to a means for distributing the loading of the power uniton the axle supports thereof.

I-Ieretofore, rail motive power units, such as locomotives, have beenknown to have a vehicle body and at least three bearing areasdistributed along the length of the vehicle body. These power units,particularly those having three or more bogies or individual axles have,however, had a problem in the distribution of the loading between thevarious axles. That is, in order to use the force of adhesion of thelocomotive, all the axles, as a rule, have been driven and have requiredan appropriate loading. However, when the power unit exerts a tractiveeffort, the end to which the effort is applied becomes loaded while theopposite end (i.e.. the front end) is relieved of load. The problem isthus to ensure that the axles which experience extra loading do notapply an excessive axle loading to the rails and that the more lightlyloaded axles are loaded equally so that optimum use is made of theadhesion force.

If the lightly loaded axles were loaded uniformly prior to applicationof the tractive effort, the reduction in loading for all the axlesexperiencing an individual reduction must be the same when the tractiveeffort is applied.

One known way of meeting these requirements is to divide a locomotivebody in the center and to interconnect the two halves, e.g. by way of aswivel joint, so that the halves can rotate relative to one anotheraround a transverse axis. Another known technique is for pairs of bogiesto be joined together by a top frame which carries the vehicle body.Also, known are adjustable springing systems which use, for example, airsprings in which requirements are set by means of appropriately adjustedcontrollers.

However, these known systems have been costly and have had a variety ofdisadvantages. For example, dividing of a vehicle body results in areduction of rigidity and introduces the risk of the two parts or halvesoscillating relative to one another in movement. Pneumatic suspensionhas been costly and requires a compressor to operate continuously, andpossibly at ahigh level.

Accordingly, it is an object of this invention to provide a motive powerunit in which the individual driving axles are loaded as required.

It is another object of the invention to load the individual drivingaxles of a motive power unit in dependence on tractive effort.

It is another object of the invention to provide an undivided rigidvehicle body having individual driving axles loaded in dependence ontractive effort.

It is another object of the invention to provide a relativelyinexpensive means of loading the driving axles of a motive power unit.

Briefly, the invention provides a motive power unit having a bodycarried at at least three bearing areas along the length of the bodywith non-variable-rate springs at one or more bearing areas andadjustable springs at at least one other bearing area. In addition, acontroller is connected to the adjustable springs to control the springforce thereof independence upon the tractive effort of the power unit.

In one embodiment, bogies are provided at each bearing area to carry thevehicle body while, in another embodiment, individual axles are mountedin a frame of the body at the bearing areas.

In another embodiment, the non-variable-rate springs are provided at theouter bearing areas while the adjustable springs are positioned at theinner bearing areas. In still another embodiment, the adjustable springsare positioned at the outer bearing areas while the non-variable-ratesprings are at the inner bearing areas.

In operation, for example, where the adjustable springs are in the innerbearing areas and the nonvariable-rate springs are at the outer bearingareas, when a tractive effort is applied to one end of the motive powerunit, e.g. the rear end, the forces of the adjustable springs aredecreased so that the spring force of these springs equal the springforce of the nonvariable-rate springs at the opposite, i.e. forward, endof the power unit. In this way, the adhesion forces of the power unitcan be effectively used. The relationship between the increase intractive effort and the decrease in adjustable spring force can beproportional or non proportional.

These and other objects of the invention will become more apparent fromthe following detailed description and appended claims taken inconjunction with the accompanying drawings in which:

FIG. 1 diagrammatically illustrates a power unit utilizing a centraladjustable spring according to the invention;

FIG. 2 diagrammatically illustrates a power unit having the adjustablesprings at the outer bearing areas according to the invention;

FIG. 3 illustratesa view similar to FIG. 1 of a power unit having areservoir for increasing the air spring volume of the central adjustingspring;

FIG. 4 graphically illustrates a proportional relationship between thetractive effort and the spring force of the adjustable spring; and

FIG. 5 graphically illustrates a non-proportional relationship betweenthe tractive effort and the spring force of the adjustable spring.

Referring to FIG. 1, a locomotive includes a vehicle body 1 and threebogies I, II, III] at separate bearing areas along the length of thebody 1 which supports the body 1. Each bogie comprises two driving axles3 which are connected in known manner to traction motors 4 and whichsupport the bodyl on suitable rails. The two outer bogies I, III haveknown steel springs 5 which are shown in diagrammatic form, whereas thecenter bogey II has air springs 6, only one of which is showndiagrammatically. The springs 5, 6 are constructed in known manner so asto provide lateral stabilization of the vehicle body 1. The bogies I,II, III also have known elements, such as deep drawbars (not shown),which equalize the loading between the two axles 3 of each bogey.

The air spring 6 is connected to a compressor 7 via an air line 11 inwhich a check valve 8, a supply air reservoir 9 and a controller 10 areinterposed.

The body 1 also includes a draw hook 12 where a tractive effort 2 isexerted as well as a pickoff 13 between the draw hook 12 and thecontroller 10 for measuring the the instantaneous tractive effort of thelocotive effort Z measured. Alternatively, the motor current can be usedas a yardstick for the tractive effort.

If the locomotive of FIG. 1 applies a tractive effort Z to the rails,since the tractive effort is exerted at the drawhook 12 some distanceabove the rails, the locomotive experiences a moment which increases theloading of the rear axlesi.e. the axles of the bogey III but decreasesthe loading of the bogies I, II. If the locomotive had merely identicaltypes of steel spring with the same spring rates, the axle loading ofbogey I would be reduced more than would the axle loading of bogey II,with the consequent risk of the wheels of bogey I slipping andappreciably reducing the tractive effort. For optimum tractive effort,the load reduction from the two bogies I, II must be uniformlydistributed so that such bogies, and therefore their axles, are allloaded equally. Of course, the axles of bogey III experience an extraloading corresponding to the same total force as the amount by which theloading of bogies I, II is reduced.

To achieve this equal loading of the two bogies I, II, the controller 10controls the force of spring 6 in de pendence upon the tractive effort,as shown in the diagram of FIG. 4. This diagram shows that the springforce P of air spring 6 decreases as the tractive effort Z increases,the decrease being so controlled by controller 10 that the spring forceP is always the same as the spring force of the spring 5 of bogey I.

Clearly, the force P can be varied stepwise instead of steplessly. Forinstance, the spring force of spring 6 can, as shown by the curve b inFIG. 5, remain constant until the tractive effort Z reaches a criticalvalue, then drop abruptly to the value for maximum tractive effort. Atwo-stage adjustment as indicated by curve in FIG. is anotherpossibility, but it must be borne in mind in such cases thatrelationships are ideal only for a number of discrete values of tractiveeffort and are only approximately correct for other values.

Referring to FIG. 2, the locomotive can alternatively be provided withtwo sets of air springs in the bogies I, III. As in the previousembodiment, the air springs 20 shown represent a set of, as a rule, twoair springs. These air springs 20 are connected via air lines 21, 22 andcontrol valves or controllers 23, 24 to a compressor 25. As in theembodiment of FIG. 1, air reservoirs 26 are disposed before the valves23, 24, check valves are disposed between the reservoirs 26 andcompressor 25 and the locomotive has a tractive-effort pickoff 13. Thepickoff 13 is connected by signal lines 27, 28 to the valves orcontrollers 23, 24 respectively. The central bogey II has a set ofconstant-rate steel springs represented by a single spring 29.

In operation, when the tractive force Z originates and then increases,the forces in the two springs 20 change to ensure ideal alterations ofaxle loading with the controllers 23, 24 providing independent controlof the spring forces for each bogey I, III. That is, the spring force,i.e. the air pressure operative in each spring of bogies I, III, mustincrease asthe tractive effort increases.

As in the embodiment of FIG. 1, the conditions referred to, i.e. equalloading of the more lightly loaded bogies I, II, is achieved. If thespringing is correctly chosen, the required load reduction can beachieved by the pressures in the springs of both bogies I, III varyingin the same pattern, so that it is theoretically possible to use eithera single controller or two identically operating and operatedcontrollers.

In addition to obtaining bogey and axle load equalization when atractive effort is applied, it is often necessary to prevent alterationof the selected loading of the bogies by track uneveness or changes ingradient, for instance, at a transition from the flat to an upgrade or adowngrade. To this end, referring to FIG. 3, an air reservoir 30representative of an extra air volume is provided to provide thiscontrol. This reservoir 30 is connected into the line 11 to the airspring 6 and the operation thereof and of the controller 10 is similarto that described above in regard to the embodiment of FIG. 1. However,the increase in air spring volume due to the presence of the reservoir30 leading to the spring 6 has a very flat rate, so that its springforce, i.e. the loading of the axles 3 of bogey II, varies little forvertical movements of bogey II.

The invention is, of course, similarly useful for motive power unitshaving more than three bogies and/or individual axles. As a rule, extracontrollers are necessary in such cases to control the extra air springsin the manner described.

The invention thus provides a motive power unit which has a relativelylow initial cost and relatively low running cost compared to othersystems using adjustable springing.

What is claimed is:

l. A rail vehicle motive power unit comprising a body;

at least three bogies for supporting said body along the length thereof;

a non-variable-rate spring disposed between at least one of said bogiesand said body;

an adjustable spring disposed between at least one other of said bogiesand said body;

a controller connected to said adjustable spring for controlling thespring force of said adjustable spring in dependence upon the tractiveeffort of said unit; and

means at one end of said body for measuring the amount of tractiveeffort applied thereat, said means being connected to said controller toemit a signal thereto in response to the measured amount of tractiveeffort for adjusting the spring force of said adjustable spring toobtain a substantially equal tractive force at said two bogies adjacentthe opposite end of said body.

2. A rail motive power unit as set forth in claim 1 which furthercomprises at least two axles on each bogie.

3. A rail motive power unit as set forth in claim 1 wherein anon-variable-rate spring is mounted at each of the outer of said bogies.

4. A rail motive power unit as set forth in claim 1 wherein anadjustable spring is mounted at each of the outer of said bogies.

5. A rail motive power unit as set forth in claim 4 which furthercomprises a pair of said controllers each connected to one of saidajustable springs respectively and to said means to impart independentcontrol.

6. A rail motive power unit as set forth in claim 1 wherein saidcontroller is connected to said adjustable spring to decrease the springforce thereof in response to an increased tractive effort whereby theloading at all bogies as have their loading reduced by said tractiveeffort is reduced to the same extent.

7. A rail motive power unit as set forth in claim 6 further comprisingan air reservoir connected between said controller and said adjustablespring for maintaining a substantially constant spring force in responseto changes in vertical movements of said respective bogie.

8. A rail motive power unit as set forth in claim 1 further comprisingmeans for maintaining a constant spring force in said adjustable springin response to changes in gradient of said body.

9. A rail motive power unit as set forth in claim 1 wherein said meansincludes a draw hook at one end of said body for application of atractive effort thereto;

a pick-off connected to said draw hook for measuring the amount oftractive effort applied thereto; and

a signal line connecting said pick off to said controller to emit saidsignal thereto.

10. A rail motive power unit comprising a body;

at least three bogies mounting said body thereon at three longitudinallyspaced bearing areas;

a pair of said adjustable springs each mounted at the outer of saidbearing areas between a respective bogie and said body;

an air reservoir connected to each adjustable spring to supply airthereto;

a pair of controllers each connected to a respective adjustable springbetween said adjustable spring and a respective air reservoir;

a draw hook at one end of said body for application of a tractive effortthereto;

a pick-off connected to said draw hook for measuring the amount oftractive efitort applied thereto; and

a pair of signal lines each connecting said pick off to a respectivecontroller to emit a signal thereto for adjustment of the spring forceof said adjustable spring connected thereto, whereby said controllersincrease the spring force of said adjustable springs in response to anincrease in tractive effort to obtain a substantially equal force insaid springs adjacent the opposite end of said body.

1. A rail vehicle motive power unit comprising a body; at least threebogies for supporting said body along the length thereof; anon-variable-rate spring disposed between at least one of said bogiesand said body; an adjustable spring disposed between at least one otherof said bogies and said body; a controller connected to said adjustablespring for controlling the spring force of said adjustable spring independence upon the tractive effort of said unit; and means at one endof said body for measuring the amount of tractive effort appliedthereat, said means being connected to said controller to emit a signalthereto in response to the measured amount of tractive effort foradjusting the spring force of said adjustable spring to obtain asubstantially equal tractive force at said two bogies adjacent theopposite end of said body.
 2. A rail motive power unit as set forth inclaim 1 which further comprises at least two axles on each bogie.
 3. Arail motive power unit as set forth in claim 1 wherein anon-variable-rate spring is mounted at each of the outer of said bogies.4. A rail motive power unit as set forth in claim 1 wherein anadjustable spring is mounted at each of the outer of said bogies.
 5. Arail motive power unit as set forth in claim 4 which further comprises apair of said controllers each connected to one of said ajustable springsrespectively and to said means to impart independent control.
 6. A railmotive power unit as set forth in claim 1 wherein said controller isconnected to said adjustable spring to decrease the spring force thereofin response to an increased tractive effort whereby the loading at allbogies as have their loading reduced by said tractive effort is reducedto the same extent.
 7. A rail motive power unit as set forth in claim 6further comprising an air reservoir connected between said controllerand said adjustable spring for maintaining a substantially constantspring force in response to changes in vertical movements of saidrespective bogie.
 8. A rail motive power unit as set forth in claim 1further comprising means for maintaining a constant spring force in saidadjustable spring in response to changes in gradient of said body.
 9. Arail motive power unit as set forth in claim 1 wherein said meansincludes a draw hook at one end of said body for application of atractive effort thereto; a pick-off connected to said draw hook formeasuring the amount of tractive effort applied thereto; and a signalline connecting said pick off to said controller to emit said signalthereto.
 10. A rail motive power unit comprising a body; at least threebogies mounting said body thereon at three longitudinally spaced bearingareas; a pair of said adjustable springs each mounted at the outer ofsaid bearing areas between a respective bogie and said body; an airreservoir connected to each adjustable spring to supply air thereto; apair of controllers each connected to a respective adjustable springbetween said adjustable spring and a respective air reservoir; a drawhook at one end of said body for application of a tractive effortthereto; a pick-off connected to said draw hook for measuring the amountof tractive effort applied thereto; and a pair of siGnal lines eachconnecting said pick off to a respective controller to emit a signalthereto for adjustment of the spring force of said adjustable springconnected thereto, whereby said controllers increase the spring force ofsaid adjustable springs in response to an increase in tractive effort toobtain a substantially equal force in said springs adjacent the oppositeend of said body.